regarding the MAC U/L bit

Oh man! Ad-blocking software has been detected! :'(

This website is run by the community, for the community... and it needs advertisements in order to keep running. Blocking our ads means your killing our stats!
Please disable your ad-block, or become a premium member to hide all advertisements and this notice.

From wikipedia

Universally administered and locally administered addresses are distinguished by setting the second-least-significant bit of the most significant byte of the address. This bit is also referred to as the U/L bit, short for Universal/Local, which identifies how the address is administered. If the bit is 0, the address is universally administered

What does it mean to be a universally administered address? How does that function in the network?

Same questions for locally administered addresses.

 

Oh man! Ad-blocking software has been detected! :'(

This website is run by the community, for the community... and it needs advertisements in order to keep running. Blocking our ads means your killing our stats!
Please disable your ad-block, or become a premium member to hide all advertisements and this notice.

Excuse very late reply. Honestly, you don't need to worry about this. What it basically means:-

"Universally administered" means the MAC address was burned into the device at manufacture. First half is the Manufacturer ID (so will be the same across many devices made by the same company), last half is device ID, which is unique to the device.
This means it is globally unique. No two devices in the world will have the same MAC. It is universally controlled and guaranteed to be unique.

"Locally administered" means someone came along and overrode the global one with something of their own. The stuff about 2-least significant bit just explains that if you're doing this, the binary has to look the right way. Some things force you to start the MAC 02-... to meet this requirement.

In my experience, in the places I've been, no one's tinkered with the MACs. For the most part, these work just fine without user intervention.